1. The Field of the Invention
The present invention relates to systems and methods for accurately measuring an amount of fluid. More specifically, the present invention is directed to systems and methods for using a measurement of the amount of gas to measure, in a sterile, reliable and accurate manner, the amount of fluid that is dispensed from or introduced into a container.
2. Background and Related Art
Since the beginning of science, practitioners have been required to measure the amount of liquid transferred from one container to another container or location. Traditional methods for performing such liquid transfer measurements have included the use of such devices as measuring cups or liquid flow meters. While each method has its own distinct and unique advantage, a number of drawbacks exist in the utilization of the traditional methods for measuring liquid transferred or dispensed from a container. As an example, the traditional methods can expose the transferred liquid to impurities within the environment, such as air-born bacteria, and allow for the introduction of human error into the measurements. The methods can also be complex and expensive, and unable to accurately measure low volumes of liquids due to varying densities and viscosities.
Additional drawbacks are specific to the application for which the liquid transfer measurements are being performed. By way of example, one area where practitioners are required to accurately measure the amount of liquid transferred or dispensed from a container is in the medical area of radiology, in which a radiopaque liquid known as xe2x80x9ccontrast mediumxe2x80x9d is inserted into a patient""s body so as to provide a contrast in density between the area of the body that is being x-rayed and the contrast medium inserted.
When fluid, such as contrast medium, is intravenously administered, it is critical that air bubbles are not inadvertently introduced into the patient""s vascular system. It is, therefore, important that the practitioner monitor and continually assess the amount of medium remaining in the container in order to prevent any possibility of inadvertently injecting air bubbles into the patient. Administering an excess amount of fluid, such as contrast medium, can also injure a patient. Due to the current expense of contrast medium, it is also very important for the practitioner dispensing the contrast medium to perform the process in a manner that results in the least amount of waste. For accurate billing and cost assessment purposes, a practitioner is required to monitor the exact amount of contrast medium that is delivered to each patient over the course of the patient""s medical procedure or hospital stay. However, monitoring the exact amount of contrast medium administered to a patient is difficult, particularly when multiple contrast medium dispensers are used or when a dispenser is shared between two patients. This inability to accurately monitor the exact amount of medium administered can result in patients being incorrectly charged. The inaccuracies complicate any determination as to the amount of useful medium remaining in a dispenser and often result in the remainder being discarded rather than being used on a new patient. Given the high cost, such waste of contrast medium can translate into significant financial losses for facilities that perform a large number of these fluid-dispensing procedures.
This need to accurately measure the amount of contrast medium dispensed is one example of the current need to accurately and reliably measure liquid that is dispensed from a container.
The present invention is directed to systems and methods for using a measurement of the amount of gas entering or exiting a container to measure, in a sterile, reliable and accurate manner, the amount of fluid that is dispensed from or introduced into a container.
Implementation of the present invention is performed in association with a non-collapsible container. The container comprises a rigid material such that as fluid is dispensed from the container and a vacuum is created, the container walls do not collapse. A measuring system that includes a sensor is in fluid communication with the container.
In one implementation of the present invention, a sensor is used for sensing the volume of the gas entering or exiting the container. The sensor can be a single sensor that performs both functions of sensing both the mass flow and the density of the gas, or can be a dual sensor wherein one sensor component senses the mass flow and another sensor component senses the density. Optionally, a measurement of the gas density can be preprogrammed into the sensor or calculating system such that the sensor only senses gas flow. The volume of gas entering or exiting the container may also be measured in a variety of different manners.
The calculating system calculates the amount of fluid dispensed from or introduced into the container based on the amount of gas flowing into or out of the container. The calculating system typically comprises an electrical system that includes a microprocessor and/or an analog-to-digital converter, but can comprise a variety of different systems, such as a mechanical system that determines the amount of gas flowing due to fluid dispensed from or introduced into a container. The fluid may comprise a liquid, such as contrast medium or a variety of different fluids.
A filtering system may optionally be used to maintain a sterile environment and to protect the sensor. Therefore, in light of the overall system, the gas entering or exiting the container is measured rather than directly measuring the amount of fluid leaving or entering the container, causing the measurement to be more accurate, less complicated, and less expensive.
Additional features and advantages of the invention will be set forth in the description that follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.